Specific Absorption Ratio Sensor (SAR sensor) is a component that is used in many electronic devices, for example, mobile phones and tablet computers are equipped with an SAR Sensor. The SAR Sensor senses whether there is a change in capacitance around it through an antenna so as to determine whether there is a human body approaching the electronic device. When a human body is approaching the electronic device, the electronic device can be controlled to reduce transmitting power, thereby lowering the SAR value to decrease radiation toward the human body.
An antenna tuning circuit is also referred to as an antenna tuner, and is an impedance matching network connecting a transmitter and an antenna, which enables an impedance match between the transmitter and the antenna, thereby having the antenna exhibit a maximal radiation power at a certain frequency. An antenna tuning circuit comprises components such as a capacitor and an inductor, and the capacitor in the antenna tuning circuit is adjustable to enable the antenna to match with respect to various frequencies, thereby increasing the bandwidth of the antenna. Antenna tuning circuits are being used in more and more electronic devices.